The stricter measures will take effect at midnight on Thursday and last for two weeks.
Nationwide on Tuesday, there were 230 cases, 90 of them in Seoul city alone.
Nine were traced to a sauna in Seocho-gu district.
Regions outside the capital have seen a rise in cases, too.
In Gwangju, Chonnam National University Hospital locked down after it confirmed 27 cases in less than a week.
When level 1.5 takes effect in the Seoul region, places that host events like weddings and funerals will have to limit the number of guests they admit.
Also, there’ll be no eating allowed at singing rooms or dancing at clubs.
Religious facilities and sporting venues will operate at 30-percent capacity.
Schools will go back to an attendance cap of two-thirds, and protests and festivals are limited to fewer than 100 people.
But some say that to effectively curb the spread, the capital should skip straight to level 2.
Under level 2, cafes and restaurants cannot have dine-in customers after 9 PM, and entertainment facilities like bars and singing rooms have to close completely.
But the health officials are conscious of the damage those measures would do to businesses.
“Under level 1.5, most businesses can continue to operate but just with a limited number of visitors. Level 2, on the other hand, would prevent many businesses from operating at all. So our day-to-day lives would be greatly restricted and threatened.”
The health authorities said that they will do their best in the interests of both the economy and stopping COVID-19 and asked for everyone’s full cooperation.
Kim Yeon-seung, Arirang News